Hi Bob, The investment coating technique mentioned by a few of
the folks here will work and many beginers like this method. The
rule the pro’s follow is “cups up” in other words, don’t let the
bubbles get trapped on their way up and out. Also, you could be
describing another problem called spauling. This is caused by
weak investment (old or improperly measured), and-or to rapid of
a burn-out, causing chunks of interior investment to fracture and
relocate, therefore allowing the metal to go where you don’t want
it…J.A…
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